Effects of Zr, Al, and Al+Zr Addition on Phase Evolution Characteristics and Strengthening Mechanisms of Fe‐42Ni‐2Y₂O₃ Oxide Dispersion Strengthening Steels Developed by Mechanical Alloying and Spark Plasma Sintering

Abstract

In the present study, Fe‐42wt.% Ni‐2wt.% Y2O3 super invar‐based steels have been explored to study the effects of Zr, Al and Zr+Al addition on phase evolution, strengthening mechanisms and mechanical behavior. Three different compositions such as Fe‐42Ni‐2Y2O3‐2Zr (2YZr), Fe‐42Ni‐2Y2O3‐2Al (2YAl), Fe‐42Ni‐2Y2O3‐2Zr‐2Al (2YAlZr) were developed by mechanical alloying (MA) followed by spark plasma sintering (SPS) at 1100 °C with an applied pressure of 60 MPa. The 2YZr alloy after SPS shows evolution of a uniform grain size ∽1.7 µm, whereas 2YAl revealed the formation of bimodal grain structure sintered under same condition. Conversely, the combined effect of Al and Zr addition resulted in the evolution of ultrafine grained structure (∽380 nm) after SPS at the same condition (i.e., at 1100 °C). The superior mechanical strength of the 2YAlZr alloy (5.3 GPa/1415 MPa) is attributed to the evolution of uniformly dispersed extremely fine (60 nm) high‐density Al‐ and Zr‐rich oxide complexes in the ultrafine grained matrix. Analysis of strengthening contributions to the yield strength found to correlate well with the experimental results and attributed to the morphology of microstructural constituents, its stability, and volume fraction of dispersoids in the matrix.This article is protected by copyright. All rights reserved.